Stepping-tube read-in circuit employing gates to selectively inhibit lower order counters to effect more efficient read-in of additional numbers



3 Sheets-Sheet 1 Feb 1957 G. o. CROWTHER ETAL STEPPING-TUBE READINCIRCUIT EMPLOYING GATES TO SELECTIVELY INHIBIT LOWER ORDER COUNTERS TOEFFECT MORE EFFICIENT READ-IN OF ADDITIONAL NUMBERS Filed Dec. 19, 1963o o y f M i v A V v m Nm zmww #NW vmww mm mm M v o W Om P I 0 mm P a ONT v M A NEW OPE w QM? MIW NI OE v fimmm 01M NEW 0? PM fi m PM L v "EiAT .lTL- MU ltg Fm PU TC. 090 N P TC. OPU PM N C. 7:. CPU m. 1 1 iv L a0 Fl fiAATII O @O W @O o 4 @x L x L A QM KT 6Q PO @m m DZ 1 o mhv O n. mi

GERALD O. CROWTHER GRAHAM F. JEYNES AGENT 3,303,384 LECTIVELY EFFICIENT3 Sheets-Sheet 5 G. O. CROWTHER ETAL AD-IN CIRCUIT EMPLOYING GATES TO sEINHIBIT LOWER ORDER COUNTERS TO EFFECT MORE READ-IN OF ADDITIONALNUMBERS STEPPING-TUBE RE "E w o O T N o M x NW a A cmw X A w 50 :w A m mw 3w 9mm m 3 AM E300 A H 09 10 mm o A Q A 9- L mmuw M w A a mmw m. Nwmmm 08 3% E Rm 0% I Em mm 0E v t E Y 5 Na No 11 E U w E -P F F U l-v T]I U w.m o I? o PA .5 7 we Q E Q L I x I I5 5 E 3 mm I 0 3.? Em A #2 Feb.7, 1967 Filed Dec. 19 1963 m miu GERALD 0. CROWTHER GRAHAM F. JEYNES BY$2 4% AGENT United States Patent 3,303 384 STEPPING-TUBE READ-IN CIRCUITEMPLOYING GATES TO SELECTIVELY INHIBIT LOWER OR- DER COUNTERS T0 EFFECTMORE EFFICIENT READ-IN 0F ADDITIONAL NUMBERS Gerald Ofi'ley Crowther andGraham Frank Jeynes, Cheam, Surrey, England, assignors to North AmericanPhilips Company, Inc., New York, N.Y.

Filed Dec. 19, 1963, Ser. No. 331,677 4 Claims. (Cl. 31584.5)

This invention relates to counting circuits and more particularly tocold-cathode stepping-tube counting-circuits which may be used in smallcomputing machines.

The term stepping tube is herein used to define a tube having anelectrode assembly comprising a common electrode, a plurality ofswitching electrodes and a plurality of further electrodes, wherein astream of electrons and ions may be caused to travel between the commonelectrode and one of the further electrodes and wherein one end of thestream of electrons may be caused to move from one to another of thefurther electrodes in a predetermined sequence by the application ofsuitable potentials to the switching electrodes.

Usually, the central electrode is circular and functions as an anode,the other electrodes being arranged in a circular row, and when in use,being returned to a potential more negative than that to which the anodeis returned. These other electrodes thus may correctly be regarded ascathodes; however, each position in the tube usually has associated withit three or four of these electrodes and it is convenient to distinguishthem by referring to those on which the glow discharge rests betweenpulses as main cathodes or cathodes and to refer to the other electrodesas guide electrodes or guides.

In known stepping tubes the transfer of the discharge from its restposition on one cathode to its rest position on the next cathode is thuseffected by means of a plurality of guide electrodes; where there aretwo guide electrodes between adjacent cathodes the guide next to thecathode in the direction of rotation of the discharge is usually termedthe first" or A guide and the next guide again in the direction ofrotation of the discharge is termed the second or B guide. Throughoutthis specification the terms A guide and B guide will be used. In theseknown tubes all the A guides are usually connected together or commonedinside the envelope and all the B guides are similarly connectedtogether; in operation the discharge is transferred in its entirety fromits rest position on one cathode to an A guide, then from the said Aguide to a B guide and finally from the B guide to the next cathode.

The invention is directed towards a provision of a circuit arrangementfor providing a read-in facility by means of which a number may be addedto a number already stored in the counting circuit.

When it is desired to add two numbers together in such a-machine, thatis to say when it is desired to add to a number already stored in aportion of the machine a second number, then it is often inconvenient toadd this number by means of single digit pulses. Thus for instancesuppose the number to be added, the second number referred to above, isa four figure number. To add this number by unit digits it will benecessary to count some thousands of digit pulses into the stored numberbefore the addition process is applied. However if the number were addedseparately units, tens, hundreds and thousands digits into theappropriate decade stages of the store, the greatest number of pulsesthen necessary would be nine for each decade or a total number ofthirty-six for the four decades. Such ice a process would obviously bemuch quicker and more convenient than adding the two numbers together bya succession of unit digits.

According to one aspect of the present invention a cold-cathodestepping-tube counting-circuit including a chain of cold-cathodestepping-tubes arranged in cascade operates to count a succession ofpulses and to store the number thus counted. Means are present betweeneach pair of successive stepping-tube stages for providing a carryfacility from one stage to the next following stage of higher order, andfor selectively inhibiting the stepping of those stages preceding aselected stage so that, when it is desired to add a second number to anumber already stored in the chain, digits can be added separately toseparate stages of the stepping-tube chain without affecting otherstages.

According to another aspect of the invention, the counting-circuitincludes means for inhibiting the operation of the earliest, lowestorder stage whereby a second number can be counted into the chainwithout stepping the said earliest stage.

Embodiments of the invention will now be described with reference to.the accompanying diagrammatic drawings in which,

FIGURE 1 is a circuit diagram of a first embodiment,

FIGURE 2 is a circuit diagram of a second embodiment, and

FIGURE 3 is a circuit diagram illustrating additional features.

Referring now to FIGURE 1 this illustrates a chain of cold-cathodestepping-tubes which are operative to count input pulses fed to thechain; these tubes will hereinafter be referred to as counting-tubes. Asdescribed in our copending applications Serial Nos. 331,676 and 331,678,both filed December 19, 1963, the counting chain is arranged to receiveA guide pulses along an A pulse line APL and B guide pulses along a Bpulse line BPL. Prepulses are supplied from a pre-pulse line PP to theninth cathodes K9 of each of the counting tubes so as to provide carrypulses from each stage to the next succeeding stage, the inter-stagecouplings each comprising a K ohm resistor R7 and a 20 pf. capacitorC10. The operation of this circuit is described in the specificationsreferred to above and will not be repeated herein except in so far as itdirectly concerns the present invention.

If it is desired to read-in a number other than 2. units number it isnecessary to inhibit all stages, prior to the stage into which thenumber is to be read, from responding to the read-in pulses. Thus forinstance if we wish to read-in the number 800 then we can do this bystepping the hundreds digit eight times but we must at the same timeensure that the tens and the units tubes are not stepped. A furtherrequirement however is that the normal carry facility from one stage tothe next succeeding stage should remain unaffected so that if we read-in800 the hundreds stage must be able, if necessary, to provide a carrypulse to step the thousands stage on when the hundreds stage reaches thedigit zero.

This facility is provided in FIGURE 1 by providing a positive line,suitably 2 volt as indicated on the figure, to which the ninth cathodeK9 of each counting tube can be returned when it is desired to inhibitstepping of the next succeeding counting tube. This is effected byproviding a resistor R10 connected to the K9 cathode of each countingtube, each resistor R10 being connectable through an individual switchS2 to a 2 volt positive line. In order to inhibit the units tube Vu frombeing stepped by read-in pulses applied along the A, the B, and thepre-pulse lines, the pre-pulses are applied to the A guides of Vathrough a first gate circuit comprising a transistor'Trl and a second'gate' Circuit comprising a transistor Tr2 and diodes D1 and D2. Thesetwo gate circuits are identical to the inter-stage gates the operationof which and the component values for which are described in theaforesaid US. Application Serial No. 331,676. The junction of eachresistor R7 and capacitor C is connected through a switch S2 to a commonprepulse line: at the input to the gate circuits preceding the unitstube Vu the resistor R7 is omitted. Certain of the circuit componentsappertaining to the units, tens" and hundreds stages have been indicatedby the suffixes u, t and h respectively.

First of all consider the operation of the circuit when it is desired tocount pulses into the units stage in a manner similar to that describedin our co-pending U.S. application 331,676. To do this the base of Trlin the gate preceding the units tube'Vu is raised to a positive voltageof 2 volts by closing switch 82a and this switches olf Trl so that itbecomes non-conducting. At the same time switch 83a is also closed sothat pre-pulses appearing on the common pre-pulse line can now beapplied through capacitor C10 to the base of Trl. When a pre-pulse nowappears on the common pre-pulse line and is applied throughS3u and C10to the base of this transistor T11 it causes Tr1 to conduct which inturn causes Tr2 to cut off and to open the gate formed by Tr2, D1 and D2thus permitting the A pulse, which follows shortly after the pre-pulse,to be applied in full to the A guides GA of tube Vu as described in theabove-mentioned application. Thus for normal counting, that is to saywhen the pulses to be counted are applied to the units stage, thecircuit functions in a way that is identical with the circuit describedin the above-mentioned application except that gate circuits areprovided not only between stepping-tube stages but also in front of thefirst stage. The provision of the resistor R7 in series with thecapacitor C10 does not substantially alter the inter-stage coupling.

Consider now a situation where it is desired to step the tens tube Vt,and to perform the usual carry operations down the chain, that is to sayin the succeeding stages. This kind of operation may arise where it isdesired, for

instance, to count into the chain a number such as 80 where the countingof eight digits each representing ten can be accomplished much morequickly than the counting of eightly digits each representing one. To dothis switches S2t and S3t are both closed so that the pre-pulses areapplied only, through C10, to the base of the transistor Trl connectedto the cathode K9 of the units tube Vu, while the base of thistransistor is biased to non-conduction by returning it to the 2 v.positive line. The resistor R7 inhibits Tr2 from clamping the left-handside of C10 to the collector voltage of Tr2. As 82a and 53a remain openthen the gate circuit preceding tube Vu remains closed. If now eightsets of pulses, each set comprising a pre-pulse an A pulse and a Bpulse, are caused to appear at the appropriate pulse lines, the tube Vtwill be caused to step eight times and any carry operation necessary inthe succeeding stages will be effected in the usual manner. 7

Similarly if it is required to count digits into the hundreds stage onlythen switches 82k and 83h are operated, all the other switches S2 and S3remaining open, and the circuit will then proceed to count pulses inhundreds.

The main features of this circuit may conveniently be summarised asfollows. First a positive pre-bias is applied to the gate circuitimmediately before the steppingtube to which the input is to be applied,so as permanently to open this gate circuit to the pre-pulses. Secondly,negative-going pre-pulses are applied to this gate circuit only and notto any of the other gate circuits. Thirdly, an inter-stage couplingcircuit is provided between each gate in order that counts can becarried" to each higher-order stage, but these coupling circuits mustinhibit the application of pro-pulses in a backward" direction.

FIGURE 2 illustrates an embodiment in which transistor TrZ'is ahigh-voltage transistor adapted to withstand a voltage of some v. ormore between its emitter and its collector. As explained in theabove-mentioned application this enables the diode D2 to be dispensedwith and the A guides GA of each tube, of which only the guides of tubeVt are shown in this figure, are connected directly to the collector ofT12 and are also returned to the v. negative line through resistor R5.In this arrangement the cathode K9 of the units tube Va is connected toa resistor R10 which in turn is connectable through switch S2t to a 2 v.positive line. This arrangement, it will be seen, is in efiect the sameas that illustrated in FIGURE 1 and the omission of diode D2 does notaffect .the portion of the circuit with which the read-in facilities areconnected.

FIGURE 3 is a further embodiment showing a circuit similar to thatillustrated in FIGURE 1 but also embodying read-out facilities and alsoshowing the connections for a chain of number-indicating tubes. In thisarrangement the circuit as shown in FIGURE 3 is in the coun position,that is to say the position in which it will receive and count normalunit pulses applied over the A, B and pre-pulse lines. When'it isdesired to read-out a number stored in the counting chain, that is tosay when this number is to be displayed upon a ,chain ofnumber-indicating tubes, switch S1 is switched to the read-out position.When it is desired to perform an addition by reading-in numbers onto thenumber already sorted in the counting-chain then switch S1 is switchedto the count position and the appropriate switches S2 are operated andthe appropriate read-in pulses are then applied to the counting-chain.Where a number of several figures, for example, three figures, is to beadded to a number already stored in the count ing-chain then it ispossible to add in the appropriate number of units digits, theappropriate number of tens digits and the appropriate number of hundredsdigits in through separate operations. For adding in units the switches82a and 53a will be closed, for adding in tens digits the switches S2:and S3t will be closed, and for adding in the hundreds digits switches82k and 83h will be closed.

Alterntaively, the units pulses can be added in in one operation and theremainder of the addition performed in another operation by applying theappropriate number of pulses to the tens stage.

What we claim is:

1. A cold cathode stepping tube counting circuit comprising a chain ofcold' cathode stepping tubes arranged in cascaded stages, means applyinga first series of counting pulses to each of said stages of said counterfor storing a first number therein, a gating circuit connected betweeneach pair of successive stepping tube stages for providing a carry froma lower tube to the next successive tube inascending order, means forapplying a second series of counting pulses to each of said stages, saidsecond series representative of a plurality of digits of amultidigit-rnultiorder number, and inhibiting means connected to saidgating means for inhibiting the passage of said second series of pulsesto those counting stages of an order lower than'the order of the applieddigit in said multidigit-multiorder number.

2. A counting-circuit as claimed in claim 1 including a common countingpulse line and wherein each of said tubes includes at least one set ofguides, and each of said gating circuits comprises a diode connectedbetween said common counting pulse line and said set of guides of thestage succeeding the gating circuit, means for applying to the diode ablocking voltage preventing the diode from passing the said countingpulses, a first transistor, means for retaining the first transistor ina first state to provide said blocking voltage to said diode, means forswitching said transistor to a second state to remove said voltage, saidmeans being operable when a carry results from the stepping tube stagepreceding the gating circuit to the stepping tube stage succeeding thegating circuit, and means for selectively unblocking one of said gatingcircuit diodes to cause counting in the stepping tube stages succeedingthe selected gating circuit.

3. A counting-circuit as claimed in claim 1 wherein each gate furtherincludes a second transistor for switching said first transistor fromsaid first state to said second state, means for applyingcounting-pulses to the second transistor, means for inhibiting responseof said second transistor to said counting pulses by applying a voltageto said transistor and means for selecting a gating circuit by removingsaid voltage from the second transistor of the selected gating circuitto cause response of said second transistor to said counting pulses.

4. A cold cathode stepping tube counting chain comprising, a pluralityof gaseous discharge tubes arranged in a cascade of successively higherorder stages, each of said tubes having a plurality of successivelyhigher order representation cathodes and at least one cycling terminalfor successively switching the said discharge along the respective ordercathodes in ascending order, means applying a cycling pulse to thecycling terminal of the first of said stages, gating meansinterconnecting the cycling terminal of each subsequently higher orderstage with the highest order cathode terminal of each preceding stage,said gating means including an input terminal for receiving controlpulses, a first transistor having input, output and common electrodes,said input electrode being coupled to said terminal and to said highestorder cathode of each of said stages but the last, a second transistorhaving input, output and common electrodes, the input electrode of saidsecond transistor coupled to the output electrode of said firsttransistor, means coupling the common electrodes of both first andsecond transistors to a reference point, a first diode coupling theoutput electrode of said second transistor to the cyling terminal of thenext successive stage in ascending order, a second diode coupling saidmeans applying a cycling pulse to the cycling terminal of said nextsuccessive stage, means for biasing said diodes such that a pulse willreach the cycling terminal of said next successive stage upon thecoincidence of first and second pulses to said first and second diodes,said second transistor switching said first transistor from said firststate to said second state, means for applying counting-pulses to thesecond transistor, means for inhibiting response of said secondtransistor to said counting pulses by applying a voltage to saidtransistor, and means for selecting a gating circuit by removing saidvoltage from the second transistor of the selected gating circuit tocause response of said second transistor to said counting pulses.

References Cited by the Examiner UNITED STATES PATENTS 2,595,045 4/1952Desch et al. 32851 X 2,714,179 7/1955 Thomas et al. 31584.6 2,793,8065/1957 Lindsmith 328-51 2,975,329 3/1961 Irving et al. 31584.6 3,212,00910/1965 Parker 32851 X ARTHUR GAUSS, Primary Examiner.

I. S. HEYMAN, Assistant Examiner.

1. A COLD CATHODE STEPPING TUBE COUNTING CIRCUIT COMPRISING A CHAIN OFCOLD CATHODE STEPPING TUBES ARRANGED IN CASCADED STAGES, MEANS APPLYINGA FIRST SERIES OF COUNTING PULSES TO EACH OF SAID STAGES OF SAID COUNTERFOR STORING A FIRST NUMBER THEREIN, A GATING CIRCUIT CONNECTED BETWEENEACH PAIR OF SUCCESSIVE STEPPEING TUBE STAGES FOR PROVIDING A CARRY FROMA LOWER TUBE TO THE NEXT SUCCESSIVE TUBE IN ASCENDING ORDER, MEANS FORAPPLYING A SECOND SERIES OF COUNTING PULSES TO EACH OF SAID STAGES, SAIDSECOND SERIES REPRESENTATIVE OF A PLURALITY OF DIGITS OF AMULTIDIGIT-MULTIORDER NUMBER, AND INHIBITING MEANS CONNECTED TO SAIDGATING MEANS FOR INHIBITING THE PASSAGE OF SAID SECOND SERIES OF PULSESTO THOSE COUNTING STAGES OF AN ORDER LOWER THAN THE ORDER OF THE APPLIEDDIGIT IN SAID MULTIDIG-MULTIORDER NUMBER.